﻿<%@ WebHandler Language="C#" Class="image" %>

using System; 
using System.Drawing; 
using System.Drawing.Imaging;
using System.Text;
using System.Web;
using System.Web.SessionState;
public class image : IHttpHandler, IRequiresSessionState
{
    
    public void ProcessRequest (HttpContext context) {

        context.Response.ContentType = "image/gif"; //建立Bitmap对象，绘图 
        Bitmap basemap = new Bitmap(200, 60);
        Graphics graph = Graphics.FromImage(basemap); 
        graph.FillRectangle(new SolidBrush(Color.Gold), 0, 0, 200, 60); 
        Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);
        Random r = new Random();
        string letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ0123456789"; 
        string letter; 
        StringBuilder s = new StringBuilder();
        //添加随机的五个字母 
        for (int x = 0; x < 5; x++)
        { 
            letter = letters.Substring(r.Next(0, letters.Length - 1), 1); 
            s.Append(letter); 
            graph.DrawString(letter, font, new SolidBrush(Color.Black), x * 38, r.Next(0, 15));
        } 
        //混淆背景
        Pen linePen = new Pen(new SolidBrush(Color.Gray), 2);
        for (int x = 0; x < 6; x++) 
            graph.DrawLine(linePen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));
        //将图片保存到输出流中 
        basemap.Save(context.Response.OutputStream, ImageFormat.Gif); 
        context.Session["CheckCode"] = s.ToString(); //如果没有实现IRequiresSessionState，则这里会出错，也无法生成图片 
        context.Response.End();
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }

}